<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .container {
      width: 800px;
      height: 800px;
      border: 1px solid #ccc;
      /* 单行文字 */
      text-align: center;
      line-height: 800px;

      /* position: relative; */

      display: flex;
      justify-content: center;
      align-items: center;
    }

    .box {
      width: 200px;
      height: 200px;
      background: rgb(184, 27, 27);
      /* position: relative;
      left: 300px; */
      /* margin: 300px auto; */

      /* position: absolute;
      left: 50%;
      top: 50%; */

      /* margin-top: -100px;
      margin-left: -100px; */
      /* transform: translate(-50%, -50%); */

    }

    .span {
      background: rgb(124, 186, 173);
    }
  </style>
</head>

<body>
  <div class="container">
    <div class="box"></div>
    <span class="span">1234567</span>
  </div>
</body>

</html>